Printing compensating for jetting amount for each of multiple types of ink drops with different sizes

Abstract

According to the present invention, for at least one specific type of ink drop from among a plurality of types of ink drops of different quantities of ink, dot data can be generated in such a way as to compensate for error of ink amount for each specific type of ink drop with reference to information representing error of ink amount for given specific type of ink drops. By means of this, even if there is deviation in error of ink amount for each of different types of ink drops, color can be reproduced more accurately.

1. A printing control apparatus for generating print data to be supplied to a print unit capable of forming one of N types of dots having different sizes at one pixel area by a selective ejection of any of the N types of ink drops onto a print medium, the N types of ink drops being different in an ink amount, N being an integer of at least 2, the apparatus comprising:
 an error information receiver configured to receive error information related to an ink amount error of at least one specific type of ink drop among the N types of ink drops, the error information being provided from the print unit; and 
 a dot data generator configured to process input image data for generating dot data representing a state of dot formation at each pixel in a printed image; 
 wherein the dot data generator is configured to generate the dot data compensated for the ink amount error with respect to each of the specific type of ink drops in response to the error information. 
 
   
   
     2. The printing control apparatus in accordance with  claim 1 , wherein
 the dot data generator comprises:
 a color converter configured to convert a color system of the input image data with a color conversion table for generating color-converted image data, the color-converted image data being represented with a plurality of color components available for the print unit; and 
 a halftone processor configured to convert a tone value of the color-converted image data to any of the N tones with respect to each pixel based on a compensated relationship between an input and an output, the input being the tone value of the color-converted image data, the output being a combination of dot recording rates for each of the N dots, the compensated relationship being compensated with the error information; wherein 
 
 the halftone processor is configured to generate the compensated relationship using a reference relationship and the error information, the reference relationship being a relationship between the combination of dot recording rates for each of the N dots and a provided tone value of the color-converted image data assuming no ink amount error. 
 
   
   
     3. The printing control apparatus in accordance with  claim 2 , wherein
 the halftone processor is configured to calculate a first ink amount and a second ink amount with respect to each of the tone values of the color-converted image data based on the reference relationship, and also to multiply a value of the first ink amount divided by the second ink amount for generating the compensated relationship, the first ink amount being an ink amount ejected per unit of area excluding the ink amount error, the second ink amount being an ink amount ejected per unit of area including the ink amount error. 
 
   
   
     4. The printing control apparatus in accordance with  claim 2 , wherein
 the halftone processor is configured to calculate a first ink amount with respect to each of the tone values of the color-converted image data based on the reference relationship, and also to adjust the reference relationship for a second ink amount to approximate to the first ink amount, the first ink amount being an ink amount ejected per unit of area excluding the ink amount error, the second ink amount being an ink amount ejected per unit of area including the ink amount error. 
 
   
   
     5. The printing control apparatus in accordance with  claim 1 , wherein
 the dot data generator comprises:
 a color converter configured to convert a color system of the input image data with a compensated color conversion table for generating color-converted image data, the color-converted image data being represented with a plurality of color components available for the print unit, the compensated color conversion table being compensated with the error information; and 
 a halftone processor configured to convert a tone value of the color-converted image data to any of the N tones with respect to each pixel based on a relationship between an input and an output, the input being the tone value of the color-converted image data, the output being a combination of dot recording rates for each of the N dots; wherein 
 
 the color converter is configured to generate the compensated color conversion table using a reference color conversion table and the error information, the reference color conversion table being set assuming no ink amount error. 
 
   
   
     6. A printing control method of generating print data to be supplied to a print unit capable of forming one of N types of dots having different sizes at one pixel area by a selective ejection of any of the N types of ink drops onto a print medium, the N types of ink drops being different in an ink amount, N being an integer of at least 2, the method comprising:
 (a) receiving error information related to an ink amount error of at least one specific type of ink drop among the N types of ink drops, the error information being provided from the print unit; and 
 (b) processing input image data for generating dot data representing a state of dot formation at each pixel in a printed image; 
 wherein the step (b) includes the step of compensating the dot data for the ink amount error with respect to each of the specific types of ink drops in response to the error information. 
 
   
   
     7. A printing method of forming one of N types of dots having different sizes at one pixel area by a selective ejection of any of the N types of ink drops onto a print medium, the N types of ink drops being different in an ink amount, N being an integer of at least 2, the method comprising:
 (a) receiving error information related to an ink amount error of at least one specific type of ink drop among the N types of ink drops, the error information being provided from a print unit; 
 (b) processing input image data for generating dot data representing a state of dot formation at each pixel in a printed image; and 
 (c) ejecting the N types of ink drops onto the print medium in response to the dot data; 
 wherein the step (b) includes the step of compensating the dot data for the ink amount error with respect to each of the specific types of ink drops in response to the error information. 
 
   
   
     8. A computer-readable recording medium, storing a computer program for causing a computer to generate print data to be supplied to a print unit capable of forming one of N types of dots having different sizes at one pixel area by a selective ejection of any of the N types of ink drops onto a print medium, the N types of ink drops being different in an ink amount, N being an integer of at least 2, the computer program comprising programs for causing the computer to perform:
 a receiving function for receiving error information related to an ink amount error of at least one specific type of ink drop among the N types of ink drops, the error information being provided from the print unit; and 
 a generating function for processing input image data for generating the dot data representing a state of dot formation at each pixel in a printed image; 
 wherein the generating function includes a function for compensating the dot data for the ink amount error with respect to each of the specific types of ink drops in response to the error information.